[compiler-rt] [compiler-rt] intercept macOs's freadlink call. (PR #83679)

[Vitaly Buka via llvm-commits]

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@@ -10299,6 +10299,25 @@ INTERCEPTOR(SSIZE_T, pwritev2, int fd, __sanitizer_iovec *iov, int iovcnt,
 #define INIT_PWRITEV2
 #endif
 
+#if SANITIZER_INTERCEPT_FREADLINK
+INTERCEPTOR(SSIZE_T, freadlink, int fd, char *buf, SIZE_T bufsiz) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, freadlink, fd, buf, bufsiz);
+  COMMON_INTERCEPTOR_FD_ACCESS(ctx, fd);
+  SSIZE_T res = REAL(freadlink)(fd, buf, bufsiz);
+  if (res > 0)
+    COMMON_INTERCEPTOR_WRITE_RANGE(ctx, buf, res);
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vitalybuka wrote:

Should this write `res + 1` or `res`?
I can't find documentation to check if termninating 0 is part of res or not.

https://github.com/llvm/llvm-project/pull/83679